Automatically reversible gear pump



sept. 26 1957 R. w. ERlKsoN ETAL 3,343,494

AUTOMATICALLY REVERSIBLE GEAR PUMP Filed Sept. l2, 1966 5 Sheets-Sheet ll l l g A e 20 1| ,lvl 2i g Q9 J8 v' I l v' l l L 56pm J7 1 E 2, 3- x zVL Sept. 26, 1967 R. w. ERIKSON mp 3,343,494

AUTOMATICALLY REVERSIBLE GEAR PUMP Filed Sept. 12, 1966 3 Sheets-Sheet 2LUC' SCP- 25, 1967 R. w. ERxKsoN ETAL 3,343,494

AUTOMATICALLY REVERSIBLE GEAR PUMP 3 Sheets-Sheet s Filed Sept. 12, 1966United States Patent O M 3,343,494 AUTOMATICALLY REVERSIBLE GEAR PUMPRobert W. Erikson and Nils Einar Swedberg, Rockford,

Ill., assignors to Snndstrand Corporation, a corporation of IllinoisFiled Sept. 12, 1956, Ser. No. 589,150 7 Claims. (Cl. 10S-126) Thisapplication is a continuation-in-part of our copending application Ser.No. 455,217, iiled May 12, 1965, now abandoned.

This invention relates generally to hydraulic pumps for delivering uidunder pressure and more particularly to a new and improved gear pump.

In compressor units a small pump is conventionally provided forsupplying lubricating fluid to the various bearings in the compressor.These lubricating pumps are connected in some manner to be driven by thecompressor drive shaft. This drive shaft is usually driven by a threephase electric motor. In the installation of such compressors thedirection of rotation of the three phase motor and hence the compressordrive shaft, depends upon how the installing electrician connects themotor to the available source. lt has been found difcult for theelectrician to connect the motor so that the compressor drive shaft andthe lubricating :pump rotate in the same direction in all installations.For this reason automatically reversible lubricating pumps have beenprovided for pumping liuid out the same outlet passage regardless of thedirection of rotation of the pump input shaft.

It is a primary object of the present invention to provide a new andimproved gear type pump which maintains a unidirectional output ilowregardless of the direction of rotation of input shaft.

Another object of the present invention is to provide a new and improvedreversible gear type pump of the type having a rotating outer geardriven by an input shaft and an inner gear meshing with the outer gearand eccentrically mounted with respect to the outer gear so that theexpanding gear teeth spaces receive inlet fluid and the contracting gearspaces compress and discharge fluid from the pump. An indexible portplate is provided adjacent the relatively rotating outer and innergears. As the pump begins rotation in one direction torque istransmitted to the port plate, which carries the inner gear, so that theport plate indexes to a position where high pressure fluid ows through aport therein to a stationary outlet passage in a member adjacent theport plate. If the input shaft begins rotation in the oppositedirection, torque is transmitted to the port plate, rotating itapproximately 180 degrees from the position noted above so that highpressure fluid flows to the stationary outlet recess even though thedrive shaft rotates in the opposite direction.

It is a further object of the present invention to provide a new andimproved gear pump of the type described above in which the indexingtorque is applied to the port plate partly by the engagement therewithby the rotating outer ring gear, and partly by a drive sleeve connectedto the ring gear and frictionally engaging a portion of the periphery ofthe port plate. The cooperation of the frictional engagement of theouter gear and the cylindrical drive sleeve with the port plate assuresthe proper indexing of the plate. Stops are provided for limiting theindexing movement of the valve plate t-o approximately 180 degrees sothat the ports therein and the pinion carried thereby reverse if thedirection of rotation of the input shaft reverses.

A still further object of the present invention is to provide a new andimproved gear pump of the type described above in which the inlet andoutlet ports are axially disposed. In this manner the pump may beconstructed so Patented Sept. 26, 1967 ICC that it fits on thecompressor shaft as a unit with all parts aligned with respect to theinput shaft. This has a decided advantage over radial porting gear pumpsin that it is unnecessary to accurately align the port plate withrespect to the surrounding housing member which in a radial pump wouldconventionally include the stationary inlet and outlet ports.

Another object of the present invention is to provide a new and improvedgear pump of the type described in which the outer ring gear is separatefrom the input shaft so that the pumping elements may be connected tothe input shaft as a unit. The cylindrical drive sleeve mentioned above,which is connected to the ring gear, projects axially therefrom so thatit may be tted over one end of the drive shaft and xed thereto and inthis manner the input shaft drives the outer ring gear through thesleeve. This provides a unitary and simplified gear pump which may befitted over and aligned with respect to the drive shaft without concernfor the Vaccurate alignment of the pumping elements with respect toother portions ofthe device.

A further `object of the present invention is to provide a new andimproved gear pump of the type described above in which the input shaftis vertically disposed to increase the frictional force between theouter ring gear and the port plate to provide the necessary indexingforce on the plate.

A still further object of the present invention is to provide a new andimproved gear pump of the type described above particularly adapted forhorizontal installations which includes a resilient spring means forbiasing the port plate into engagement with the .ring gear so that thering gear exerts a suicient frictional force on the port plate to assureproper indexing thereof.

Another object of the present invention is to provide a new and improvedgear pump of the type described suitable for use with outer .and innergears of either the well known crescent type or the gear rotor type inwhich no crescent is utilized.

A further object of the present invention is to provide an improved gearpump of the type described above with novel means for relievingexcessive uid pressure.

Other and further objects of the present invention will be readilyapparent from the following detailed description taken in connectionwith accompanying drawings, in which:

FIG. 1 is a longitudinal section of a gear pump embodying the presentinvention on a vertical compressor shaft Within a reservoir in thecompressor;

FIG. 2 is a cross-section, taken generally along line 2 2 of FIG. 1,showing eccentrically mounted gears and a crescent in the space betweenthe gears;

FlG. 3 is a cross-section taken generally along line 3 3 yof FIG. 1illustrating one face of the port plate;

FIG. 4 is a cross-section taken generally along line 4 4 of FIG. 1showing one face of the cover plate;

FIG. 5 is a Ifragmentary view taken generally along line 5 5 in FIG. 1showing the other side of the port plate;

FIG. 6 is a longitudinal section of another form of the presentinvention particularly suited for use with horizontal compressor shafts;

FIG. 7 is an elevational view, partly in cross-section, of still anotherform of the invention with gear rotor type gears;

FIG. 8 is a longitudinal section of another form of the presentinvention;

FIG. 9 is a cross-section taken generally along line 9 9 in FIG. 8showing one side of the cover plate; and FIG. 10 is a cross-sectiontaken generally along line 10 10 of FIG. 8 showing the gear assembly.

VWhile illustrative embodiments of the present invention are shown anddescribed in detail herein it should be understood that the presentinvention'is susceptible of embodiment in many different forms and thatthe embodiments'illustrated are to be consideredan exemplifica- Vtion ofthe principles of the invention and are not intended to` limit theinvention thereto. The scope of the invention will be pointed. out inthe appended claims.

Referring to the drawings and particularly to FIG. l, a verticallydisposed shaft 10 is the main drive shaft for a compressor, the detailsof which form no part of the present invention and are therefore notshown. Suffice it to state that the shaft 10 may be driven by a suitablethree phaser electric motor. A reservoir is located within thevcompressor housing 11 and holds a suitable supply of lubricating uid forthe various bearings in the compressor.

The present hydraulic gear pump generally designated by the numeral 14is mounted on the outboard end of the compressor shaft 10. Shaft 10drives the pump 14 which draws fluid from withinrthe reservoir 11 andpumps fluid through a'central passage 15 in shaft 10 to the variousbearing locations. A generally cylindrical housing member 17 has amounting ange 18 thereon adapted to be xed to a stationary portion ofthe compressor by suitable fastening means (not shown). A bore 20 isprovided in the upper end of the housing 17 for a bearing 21 whichsurrounds vthe outboard end of the input shaft 10. The outboard end ofthe housing 17 has a bore 22 therein larger than and aligned with thebore 20.

A generally cylindrical cover plate or member 25 closes the housing 17,and defines stationary inlet and outlet ports for the gear pump, asshown in FIGS.V 1 and 4. Suit-V able threaded fasteners 26 fix the coverplate 25 to the housing 17. As shown more clearly in FIG. 4 an inletport 27 extends through the cover member 25 and is in constantcommunication with fluid in the reservoir 11. A generally T-shapedoutlet recess 28 is formed in the inside surface 29 of the cover member25. Recess 28 includes a central leg 30 symmetrical about the center ofthe cover member and a radially projecting leg 31. As will appear moreclearly hereinafter fluid flows from the reservoir through inlet port 27to the pump and from the pump through outletrecess 2.8 regardless of thedirection of rotation of input shaft 10. A stop pin 33 is iixed Withinthe cover member 25 and extends inwardly towards the shaft 10 a shortdistance as shown in FIGS. 1, 4 and 5.

A generally cylindrical indexible port plate 35 is provided formaintaining the high pressure outlet of the pump 14 in communicationwith outlet recess 28. AS shown in solid lines in FIG. 3, two generallyarcuate ports 37 and 38 are provided in the inwardly facing surface ofthe port plate 35. Ports 37 and 38 may be either outletl or inlet portsdepending upon the direction of rotation of input shaft 10.Diametrically opposed passages 39 and 40 communicate with the ports 37and 38, respectively, and extend through to the outward face of the portplate 35. Passages 39 and 40 are spaced from the center of the portplate 35 a distance to communicate with either inlet port 27 or the leg31 of the outlet recess 28 in the cover member 25.

As shown more clearly in FIG. the port plate 35 has an outwardly facingperipheral recess 42 extending approximately 180 degrees plus the Widthof the stop pin 33. The recess 42 slidably receives the stop pin 33 sothat, as shown in FIG. 5, the pin 33 will prevent counterclockwisemovement of the port plate 35k beyond the position shown. Uponclockwisel rotation of the port plate 35, pin 33 will prevent rotationof the port plate beyond the positionrwhere the passages 39 and 40 arereversed as shown in broken lines in FIG. 3.

A hollow shaft 44 is xed within and extends through the port plate 35projecting therefrom to the outboard end of the input shaft 10. Theinterior of the hollow shaft 44 continuously communicates with theelongated leg 30 of the outlet recess 28 and the passage 15 in the driveshaft 10. Note that the axis of shaft 44 is spaced fromV the axis of theinput shaft 10 so that depending upon the indexed position of the portplate 35, the interior'of shaft 44 will be aligned with either the upperor the lowerend of the recess leg 30 in the cover member 25.

An outer ring ygear 46 is provided with inwardly di- Y rected spacedteeth 47. Gear 46 is symmetrical about the axis of rotation of inputshaft 10 and is driven thereby by a cylindrical drive sleeve 49surrounding and engaging the outboard end of the input'shaft 10,'theperiphery of the outer ring gear 46, and a portion of the indexible portplate 35. Sleeve 49 is pinned to the input Vshaft 10 and fixed bysuitable means to the ring gear 46 so that the outer gear is drivencontinuously by shaft 10. Sleeve 49 slidably engages the periphery ofthe port plate 35 to support the same and to assist in indexing the portplate. Ring gear 46 has a radial surface 51 which frictionally engagesthe inward face of the port plate 35 to also assist in indexing the portplate. It should be understood that the indexing of the port plate 35occurs only during pump starting and that during normal runningoperation the port plate 35 remains stationary `and the ring gear 46 andthe drive sleeve 49 rotate with respect to the port plate 35.

The bore 22 in the housing is spaced from the sleeve 49 so that it doesnot retard rotation of the sleeve or the indexing of the port plate 35.

An internal pinion or gear 53 is rotatably mounted on the hollow shaft44 and has outwardly extending teeth 54 meshing with the teeth 47 on theouter gear 46 asY shown in FIGS. l and 2. As the pinion or roller gear53 Y tion in this type of pump of sealing -the low pressure area 0rspaces from the high pressure area. As shown in FIG. 2 and assuming thatring gear 46 is rotating in a clock- Wise direction, low pressure fluidwill be drawn in from port 37 in the valve plate and carried by thespaces be tween the gears which in association with the crescent 56define chambers, to the contracting area of the gears adjacent the port38 where the fluid is compressed and discharged through the port. If anexcessive nid pressure is developed in the contracting lluidV chambersbetween the gears 46 and 53, the hydraulic force acting. between theport plate 35 and cover member 25 will lift the port plate slightly (theplay in shaft 10 permits the upward movement) from sealing engagementwith the cover plate 25 permitting nid to escape into the low pressurebore 22, thus relieving the excessive pressure. Fluidy leakage may alsooccur due to separation between the gears and the port plate or thegears and the input shaft, and in these instances the high and lowpressure chambers between the gears are short circuited.

One of the advantages of the present device is that the pump 14 may bemounted on the outboard end of' the compressor shaft 10 withoutmaintaining an accurate alignment between the port plate 35 or the gearswithY the stationary cover member 2,5 which defines the stationaryoutlet port. More particularly, the indexible port i plate 35 andthegears 46 and 53 may be fitted as an aligned unit onV the end of thecompressor shaft simply by fitting the drive sleeve 49 over the shaftand fixing it thereto. Thisserves to align not only the ring gear 46with respect to the shaft, but also the port plate 35 so that duringindexing thereof it rotates about the axis of shaft 10. Smallmisalignmentsv between the port plate 35V S and the inlet and outletports in the cover member 25 do not adversely affect the operation ofthe pump.

While the operation of the present device as shown in FIGS. 1 to 5 isbelieved clear from the description above, it may be helpful to reviewthe automatic reversal on clockwise and counterclockwise rotation of theinput shaft 10. Assume iirst that the input shaft 10 begins rotation ina clockwise direction as viewed in FIG. 3. The vertically disposed shaft10 through the sleeve 49 begins rotating the outer ring gear 46. At thesame time the frictional engagement of sleeve 49 with the periphery ofthe port plate 35 and the frictional engagement of radial surface 51 ofring gear 46 with the radial surface of port plate 35 serve to index theport plate in a clockwise direction until the end of recess 42 engagesthe pin 33, which serves to stop the port plate in the position shown inFIGS. l, 3 and 5. It should be noted that the weight of the verticalshaft 10 on the ring gear 46 provides frictional force between the face51 and the valve plate to aid proper indexing and to prevent axialseparation between the port plate and the cover, the port plate and thegears, and the gears and the input shaft, in the embodiment shown inFIGS. l to 5. In this position, port 7 and passage 39 communicate withinlet port 27 and the diverging or expanding spaces between the gears 46and 53. High pressure uid from the converging spaces, which areapproximately diametrically opposed to the diverging spaces as shown inFIG. 2, pass through port 38, outlet passage 40 and into the outletrecess 28. High pressure fluid in the outlet recess 28 flows through thehollow shaft 44 and into the axial passage 15 in the compressor shaft 10to the various bearing locations for lubrication thereof.

On the other hand assume that during installation the -motor driving thecompressor shaft 10 is connected to rotate the shaft in acounterclockwise direction as viewed in FIG. 3. Also assume that thevarious pump parts are initially in the positions shown in FIGS. 1 to 5at rest. Shaft 10 through the drive sleeve 49 lbegins rotating the outergear 46 about the axis of shaft 10. At the same time the outer gear 46and the sleeve 49 frictioually engage the valve plate 35 and rotate itin a counterclockwise direction until the stop 33 abuts the opposite endof the recess 42, thereby stopping the valve plate 35. The valve platethen assumes the position shown in dotted lines in FIG. 3. Note thatduring this indexing movement of the valve plate that the pinion shaft44 and the crescent 56 also index 180 degrees, as they are fixed to theport plate 35. Fluid then enters the pump through inlet port 27 in thecover plate 25 but now ows to the expanding gear spaces through port 38in the valve plate which is then aligned with the inlet port 27. Highpressure fluid owing from the gears passes through port 37 in the valveplate and into the recess 28, the leg portion 31 of which is thenaligned with passage 39. High pressure fluid in recess 28 flows throughthe hollow shaft 44 and passage 15 in shaft 10 in the same manner as inthe clockwise operation described above.

In this manner the present device maintains a unidirectional outputthrough a stationary outlet passage by effectively indexing the gearsand port plate so that the high pressure and low pressure ports in thevalve plate always communicate respectively with the outlet and theinlet ports in a stationary port member regardless of the direction ofrotation of the pump input shaft.

In some installations it is desirable to provide a gear pump of the typedescribed adapted to be driven by a horizontally oriented compressordrive shaft. Such a pump is shown in FIG. 6 incorporating the principlesof the present invention. The parts in FIG. 6 which are the same as theparts in FIGS. l to are designated with like reference numerals. A pumphousing 18 is provided similar in construction to the housing 17 exceptthat it has an axial extension 60 with a counterbore 22 therein. Aradial inlet passage 62 extends through the housing 6 18 and is adaptedto carry low pressure fluid to the pump 14. In place of the stationarycover member 25 in the FIGS. l to 5 embodiment, a non-rotatable, axiallyslidable valve member is provided in bore 22'. A stop pin 33', fixedwithin the valve member 25', slides within the recess 42 in theindexible valve plate 35 in the same manner as in the pump 14. The stoppin 33 performs the additional function of preventing rotation of thevalve member 25' without retarding its axial movement. For this purposepin 33 slides within an axial groove 61 in the bottom of bore 22.

The cover plate 63 encloses the pump and is fixed to the open end ofhousing member 18' by suitable threaded fasteners 65. A taperedcompression spring 66 engages the inside surface of the cover 63 and isseated at its other end in a central recess in valve member 25. In thismanner the valve member 25 is continuously urged into engagement withthe face of the indexible port plate 35. If the pump 14' develops anexcessive fluid pressure, the force of hydraulic uid acting againstvalve member 25 will move it slightly axially against the force ofcompression spring 66 permitting iiuid leakage between the valve memberand the face of the port plate 35, thus relieving the excessivepressure. Fluid leakage may also occur due to separation between theport plate and the gears or between the gears and the input shaft, andin these instances the high and low pressure chambers are shortcircuited.

The operation of the FIG. 6 embodiment is the same as that of the FIGS.l to 5 embodiment, except that the frictional indexing force of gearface 51 on the indexible port plate 35 and the sealing engagementbetween the parts is produced as a result of the biasing effect ofspring 66. In this manner the present device is usable as well inhorizontal installations.

In some installations it may =be desirable to eliminate the inner gearsupport shaft 44 in both the FIGS. 1 and 6 embodiments, particularlywhen the pump application requires low discharge pressures. In such acase, the inner gear 53 would be supported and float between the outergear 46 and the crescent 56. Discharge fluid from the pump would owthrough a central bore in the inner gear and a complementary bore in theport plate 35, rather than through hollow shaft 44.

It should be understood that the principles of the present invention areapplicable not only to crescent-type gear pumps such as shown in FIGS. 1to 6, but also to gear rotor pumps of the type in which the inner andouter gear teeth are in sliding contact over the non-meshing arc of thegears. The outer and inner gear elements 70 and 71 respectively of sucha gear rotor are shown in FIG. 7. In a gear rotor as opposed to acrescent pump, the gear teeth are elongated and shaped so that theengagement between the outer and inner gear teeth provide the neces-Sary sealing between the low and high pressure sides of the pump. Nocrescent is necessary in this type of pump. When used in the presentpumping device, the outer gear member 70 would be driven by thecylindrical drive sleeve 49 in the same manner as outer ring gear 46.The inner gear 71 would be rotatably mounted on pinion shaft 44 in thesame manner as inner gear 53. The operation of the gear rotor pump wouldbe substantially the same as that described above.

The hydraulic unit shown in FIGS. 8 to 10 is generally Y similar inconstruction and operation to those described above except for theprovision of a separate resiliently brilased sealing plate between thegears and the compressor s aft.

The pump 114 is seen to include a housing member 118 forming part of thehousing of an associated compressor having a sleeve bearing 121supporting the outboard end of compressor shaft 110. Shaft has asuitable center bore 115 which serves as the outlet passage for the pumpin either direction of rotation. The housing member 118 has a centralrecess 122 for receiving the pumpingy elements and an inlet passage 162communicating with the recess. A cover member 125 is fixed to therecessed end of the housing 118, andy has formed therein a chamber-'127kcommunicating with recess 122 and inlet passage 162. Chamber 1 27extends radially and communicates with an arcuatel inlet portY 127A alsoformed in the cover 125. Opposite the port 127A (which is a low pressureport) is an arcuate port 128 which is a high pressure port in the cover125.k Port 128 continuously communicates with a radial passage or recess131 which communicates continuously withthe outlet passage 115 in theshaft 110.

Fixed to the end of shaft 110k are pumping elements,

similar to that shownV in the FIG. 7 embodiment includ-. ing sleeve 149,outer gear 70, inner gear 71, port plate 135 andy hollow shaft 144. Pin133'is mounted in cover plate 125 and limits indexing movement of theport plate, 135 in a manner similar to that described above with theother embodiments.

In the FIGS. 8 to l() embodiment, the outer gear is somewhat lar-gerthan the outer diameter of shaft 110 so that a suitable annular adapter149A is provided fixed to shaft 110 and sleeve 149 by radially extendingkey pins 150.

This embodiment is also somewhat different from the others in that thegear elements are spaced from the end of compressor shaft 11,0 and asealing p late 160 is located therebetween with one face thereofsealingly engaging the gears 70 and 71. Shaft 110 has a counterbore 162in the end thereof receiving a coiled compression spring 163 whichbiases a hollow piston 164 against the sealing plate 16,0, thus urgingthe plate against the gears and maintaining sealing engagement betweenthe parts. If an excessive iuid pressure develops in the outlet of thepump, i.e. passage 131 and hollow shaft 144, fluid pressure actingagainst .piston 144 and plate 160 will urge the sealing plate away fromthe gears against the force of spring 163 permitting uid to leak betweenthe plate and the gears and into the low pressure recess 122 throughslot 166 in shaft 110 and also between high and low pressure liuidlchambers.

The operation of the embodiment of FIGS. 8 to 10 is substantially thesame as that described above with reference to FIGS. l to 7'.

It should be understood that the present invention is not limited to usewith a compressor and finds applicability in many types of rotatingmachinery.

We claim:

1. In a gear pump, the combination comprising: an input Shaft rotatableuabout an axis, an outer ring gear adjacent one end of said input shaftand driven thereby, an indexible port plate slidably engaging said outerring gear and having two generally arcuate ports extending axiallytherethrough, said port plate having an arcuate recess in the peripherythereof extending substantially 180 degrees, a hollow shaft mounted insaid port plate and extending within said ring gear, said hollow shafthaving an axis spaced from said input shaft axis, an inner pinion gearmounted for rotation'on said hollow shaftV and meshing with said outerring gear, a passage in said input shaft communicating with the interiorof said hollow shaft adapted to convey uid fromy the pump, a relativelystationary cover member engaging one side of said port plate, aprojection on said cover member extending into said port plate recessfor limiting the indexing movement thereof whereby when the input shaftrotates the port plate,V the hollow shaft and inner gear rotateapproximately 180 .degrees to reverse the location of the arcuate ports,-an

outlet recess in said cover member in continuous communication with theinterior of said hollow shaft, said outlet recess extending radially insaid cover member to selectively communicate with said arcuate ports insaid port plate, an inlet passage in said cover member located toselectively communicate with the arcuate ports in said Vport plate,whereby inlet uid enters through said inlet passage and passes throughone of said arcuate ports, and high vpressure outlet liuid passesthrough one of saidy arcuate ports, into said outlet recess, throughsaid hollow shaft and out said input shaft passage regardless of theydirection of rotation of said inputvshaft.

2. A combination as defined in claim 1, wherein said Y outer ring gearis separatefrom said in-put shaft and llasV an outer Ydiametersubstantially equalV to the input shaft diameter, a cylindrical sleevesurrounding a portion ofsaid input shaft and said outer ring gear, saidsleeveVY being -xed to said input shaft and said gear t-o transfer Ytorque therebetween, said sleeve extending around a portion of said portplate and supporting said plate for rotation about the axis of saidinput shaft, said sleeve slidable Vand frictionally engaging Vsaid portplate so that the sleeve indexes said port plate,y a housing surroundingsaid gears and port plate, said cover member being fixed to said khousing member, the inner surface of said housing being spaced from saidsleeve Iand port plate so that the port plate may be readily indexed.

3. In a gear pump, the combination comprising: an input shaft adapted tobe rotated about an axis, an outer gear driven by said inputY shaft, aninner gear meshing with said outer gear and rotatable about an axisspaced from said input shaft axis, anV indexible port plate adjacentsaid gears having ports therein adapted to convey uid to and from, saidgears, said inner gear axis being fixed with respect to said` portplate, a relativel stationary port member having inlet and outlet portstherein adapted to selectively communicate with said indexible ports tomaint-ain a unidirectional pump output irrespective of the direction ofrotation of said input shaft, means separate from said stationary portmember for supporting said port plate for rotation about the input shaftaxis to assure the propel alignment therebetween, said outer ring gearbeing separate from said input shaft, and mean-s for connecting andaligning said outer ring to said shaft whereby the port plate, the innergear, and the outer gear may be connected as a unit and aligned withrespect to the input shaft.

4. A combination as defined in claim 3, and further including means forrelieving excessive pressure in said outlet port.

`5. A combination as defined in claim 4 wherein said means for relievingexcessive pressure in said outlet port includes a resiliently biasedsealing plate between the end of said input shaft and said gears.

6. Ina gear pump the combination comprising: an outer gear member,.sleeve means su-rronnding and xed to said outer gear member andextending axially therefrom, means for rotatably fixing said sleevemeans around an input shaft so that the gear pump is aligned therewith,an indexible plate adjacent said outer gear, said sleeve means extendingaxially from said outer gear around said indexible plate for radiallysupporting the same, said sleeve fric-. tionally engaging said plate, aninner gear meshing with said outer gear and mounted for rotation aboutan axis spaced from the axis of said outer gear, means for maintainingthe axis for rotation of said inner gear stationary with respect to saidindexibleV plate, said inner and outer gears defining upon relativerotation therebetween expanding and contracting fluid chambers, inletport means for conveying liuid to the expanding fluid chambers, outletport means for conveying liuid from the contracting fluid chambers, and-means'forlimiting the indexing movement of said Vindexible plateV sothat the contracting iiuidchambers communicate with said output portmeans regardless of the direction of rotation of'said outer gearmember.V

7. In a Vgear, pump, the combination comprising: an input shaft adaptedto be rotated about an axis, an outer gear driven by said input shaft,an inner gear meshing with said outer gear and rotatable about an axisspaced from said input shaft axis, :an yindexible port plate adjacentsaid gears having ports therein adapted to convey iiuid to and from saidgears, said inner gear axis being fixed with respect Ito said portplate, a relatively stationary port member having inlet and outletIports therein adapted to selectively communicate with said indexibleports to maintain a unidirectional pump `output irrespective of thedirection of rotate of said input shaft, means separate from saidstationary port Imember -or supporting said port plate for rotationabout the input shaft axis to assure the proper alignment therebetween,said means for supporting said port plate :and said means for connectingthe outer gear to the input shaft including a cylindrical sleevesurrounding a portion of said input shaft and fixed with respectthereto, said sleeve extending around said outer gear and xed withrespect thereto, and said sleeve further extending :around a portion ofsaid port plate and frietionally engaging the lperiphery thereof.

References Cited UNITED 2/1939 3/1939 12/1940 12/1949 ll/l954 10/19579/1959 1/1965 9/1965 STATES PATENTS Kempton et al 103-117 Neeson 10B-126Neeson 103-117 Wentling 103-126 Seavey 103--117 Hoekstra.

Gerteis.

Phelps et al. 103-126 Garrison et al 103-126 DONLEY T. STOCKING, PrimaryExaminer.

l5 W. I. GOODLIN, Assistant Examiner.

Pf3-1050 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION PatentNo. 3 343 494 Dated September 26 1967 IUVEDLOS) Pobert Erikson and NilsEinar Swedberg It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

In claim 3, column 8, line 28, cancel "relativel" and substitutetherefor relatively line 35 cancel "ring"; line 37, cancel'ring andinsert gear In the Assignment, please cancel "Sundstrand Corporation, anIllinois corporation" and insert the correct assignee as SundstrandCorporation, a Delaware corporation SIGNED AND SEALED MAR 2 4.1970

(SEAL) Attest:

1. IN A GEAR PUMP, THE COMBINATION COMPRISING: AN INPUT SHAFT ROTATABLEABOUT AN AXIS, AN OUTER RING GEAR ADJACENT ONE END OF SAID INPUT SHAFTAND DRIVEN THEREBY, AN INDEXIBLE PORT PLATE SLIDABLY ENGAGING SAID OUTERRING GEAR AND HAVING TWO GENERALLY ARCUATE PORTS EXTENDING AXIALLYTHERETHROUGH, SAID PORT PLATE HAVING AN ARCUATE RECESS IN THE PERIPHERYTHEREOF EXTENDING SUBSTANTIALLY 180 DEGREES, A HOLLOW SHAFT MOUNTED INSAID PORT AND EXTENDING WITHIN SAID RING GEAR, SAID HOLLOW SHAFT HAVINGAN AXIS SPACED FROM SAID INPUT SHAFT AXIS, AN INNER PINION GEAR MOUNTEDFOR ROTATION ON SAID HOLLOW SHAFT AND MESHING WITH SAID OUTER RING GEAR,A PASSAGE IN SAID INPUT SHAFT COMMUNICATING WITH THE INTERIOR OF SAIDHOLLOW SHAFT ADAPTED TO CONVEY FLUID FROM THE PUMP, A RELATIVELYSTATIONARY COVER MEMBER ENGAGING ONE SIDE OF SAID PORT PLATE, APROJECTION ON SAID COVER MEMBER EXTENDING INTO SAID PORT PLATE RECESSFOR LIMITING THE INDEXING MOVEMENT THEREOF WHEREBY WHEN THE INPUT SHAFTROTATES THE PORT PLATE,